New study suggests Pluto started out with a liquid ocean

The video explores the hypothesis that Pluto began with a subsurface ocean that has been freezing over time. This theory is supported by images from NASA's New Horizons mission, which show surface features indicating expansion due to ocean freezing. Pluto is believed to have a liquid ocean beneath its icy surface, with heat generated by colliding rocks and radioactive elements. The study also suggests that other large Kuiper belt objects, like Eris, Haumea, and Makemake, may have had liquid oceans.

What role do radioactive elements play in the formation of heat on Pluto?

What other objects in the Kuiper belt are mentioned to possibly have held liquid oceans?